Microbial strain data are being entered into a data bank to provide: data on specific organisms, identification of unknown isolates, cluster analysis definition of parameters of taxa, data management and report writing aids, aids in quality control of tests, methods, and laboratories, and communication of data via common format. Data files of primary data on microorganisms found in the oral cavity and related types are established, providing a resource for asking both ecological and epidemiological questions in dental research. Coding conventions have been developed to relate oral clinical parameters with the incidence and distribution patterns of specific microflora. Thus, indicator organisms for potential and/or on-going disease states can be found for diagnostic purposes. The Microbial Information System programs being developed in a related project are being used to enter, retrieve, and analyze the data for epidemiological, diagnostic, taxonomic, and ecological uses. The long term goal is to establish a worldwide data network at a series of cooperating centers. The original bacterial system now includes the algae, yeasts, molds, protozoa, and hybridomas.